CHICAGO — As the battle for middle-class voters heats up, Mitt Romney made the case this week that President Barack Obama is dismantling a crown jewel of the Clinton administration: bipartisan welfare reform.

Stumping in Obama’s home state on Tuesday, Romney hit the president for the removal of some work requirements from federal welfare regulations. And he once again tried to drive a wedge between Obama and former President Bill Clinton, who is stumping on behalf of Obama and will introduce the president at the Democratic National Convention in September.

“One of the things that happened in the last couple of decades was one of the greatest bipartisan successes we’ve seen, and that was President Bill Clinton and Republicans coming together to reform welfare,” Romney said during a visit to ACME Industries. “They reformed welfare not just to save money, more importantly, they reformed welfare to encourage people to work.”

The reform, the presumptive GOP nominee argued, “put work back into welfare,” slashing the case load “in half” and decreasing poverty rates.

”That was a great accomplishment,” Romney stated. “I hope you understand that President Obama in just the last few days has tried to reverse that accomplishment by taking the work requirement out of welfare. That is wrong. If I’m president, I’ll put work back in welfare.”

Romney was referring to an executive action by Obama last month making changes to the requirements for states to get federal welfare funds, a move the White House argued gives states more flexibility and reduces paperwork while keeping incentives to help people find jobs. Republicans called foul, saying it will simply allow states to cut welfare checks to people who aren’t working.

Obama’s camp argued that the new regulations still require work for recipients, but give states more flexibility in a bad economy.

“Mitt Romney continues to make statements that he knows are both untrue and hypocritical,” Obama spokeswoman Lis Smith said. “The Obama administration, working with the Republican governors of states like Nevada and Utah, is giving states additional flexibility only if they move more people from welfare to work — not fewer.”

The Obama campaign also accused Romney of doing the same thing when he was governor.

“Mitt Romney petitioned the federal government for waivers that would have let people stay on welfare for an indefinite period, ending welfare reform as we know it, and even created a program that handed out free cars to welfare recipients,” Smith said.

The newest charge comes as Romney tries to get his campaign back on track after his trip to Europe left it on the defensive and responding to a series of gaffes and missteps. The welfare reform push will be a central message when the presumptive GOP nominee embarks on a bus tour through Virginia, North Carolina, Florida and Ohio this weekend.

It’s also the latest attempt by the Romney camp to drive a wedge between Obama and Clinton, who signed landmark bipartisan welfare reform legislation in 1996. Republicans have set their sights on Clinton supporters — particularly white, middle-class men — who are unhappy about the direction of the economy and out of step with liberal social positions.

A television ad released by Romney’s campaign on Tuesday morning begins by featuring a smiling Clinton signing the 1996 welfare reform law with the text “unprecedented success” next to him.

Obama’s campaign continues to rely heavily on Clinton, who will officially nominate Obama at the Democratic National Convention in Charlotte next month. And the former president has helped fundraise for the Obama reelection effort.

But Romney has been trying to distinguish the two Democrats, recently saying Obama has departed from Clinton’s promise that the days of big government are over.

Both campaigns have made clear that middle-class voters are a prime target in 2012.

Obama will travel to Colorado on Wednesday to deliver remarks “to lay out a vision to restore middle-class economic security.” And last week the president went on the attack, using a nonpartisan think tank report to accuse Romney of proposing a tax plan that would shift the tax burden to the middle class.

With this new approach, Romney is trying to appeal to middle-class voters after months of complaining that the wealthy and successful are under attack by the Obama administration. The newest broadside argues that Obama is trying to give handouts to the poor at the expense of the middle class.

“Middle-class Americans are working harder and harder to make ends meet. Under President Obama, they have fewer jobs and less take-home pay,” Saul said. “And now, President Obama wants to take their hard-earned tax dollars and give it to welfare recipients without work requirements. “

It’s not a new theme of attack for Republicans.

During the primary, Newt Gingrich came under attack when he declared Obama the “food stamp president” during a debate. Gingrich, who was House speaker when the welfare reform was passed in 1996, argued that Obama had placed more people on food stamps than any president in American history, deriding government handouts.

But Romney is taking a more nuanced approach, staying away from inflammatory language and sticking with an economic message.

“This policy change undermines the very premise of welfare reform. It is an insult to Americans on welfare who are looking for an opportunity to build better lives for themselves,” Romney policy adviser Lanhee Chen wrote in a memo released Tuesday morning. “And it is a kick in the gut to the millions of hard-working middle-class taxpayers struggling in today’s economy, working more for less but always preferring self-sufficiency to a government handout.”